The initial report was a hyperextended knee. Surgery had not been scheduled as of Sunday afternoon, team spokesman Brian Olive said.

This puts the Celtics' already wayward season into a what-now position. The team doesn't really have a backup point guard, with Jason Terry the closest approximation to one. Leandro Barbosa, too, could warrant more playing time. The Celtics started Courtney Lee in Rondo's place on Sunday, but that was mostly because the matchups made sense against the Miami Heat.

Rondo was voted as a starter for the 2013 All-Star Game. He is averaging 13.7 points and a league-best 11.1 assists, and was the lone bright spot in the Celtics' run of poor play — he had back-to-back triple-doubles on Thursday and Friday.